Lee County, which encompasses Fort Myers, accounts for most of the fatalities.
The remnants of Ian are charging up the East Coast on Saturday after making landfall as a Category 1 hurricane in South Carolina on Friday afternoon.
The monster storm made its first U.S. landfall on Wednesday on Florida's west coast as a powerful Category 4 hurricane, shredding homes with ferocious winds topping 150 mph. Florida's death toll has climbed to at least 81, according to information from local officials.
A Flash Flood Emergency has been issued for parts of Sarasota, Manatee, Desoto, Hardee and Highlands counties in west-central Florida, with other areas experiencing life-threatening flash flooding.
Between 12 to 19 inches of rain has already fallen in the area.
-ABC News' Daniel Peck
As Hurricane Ian makes its way across Florida, counties are assessing the devastation left by the storm.
In a Wednesday night press conference, Lee County Sheriff Carmine Marceno said that Ian hit the county extremely hard.
Marceno said he'd gotten reports of compromised homes and businesses and of vehicles floating into the ocean.
Officials said part of Fort Myers, which is in Lee County, was "decimated" by Hurricane Ian.
Marceno said residents are in need, and the county will respond to emergency calls once it's safe.
-ABC News' William Gretsky
Hurricane Ian continues to gradually weaken as of 10 p.m. ET, with maximum sustained winds now down to 100 mph. The storm is moving to the north-northeast at 8 mph, and its center is currently about 80 miles south of Orlando.
The Florida Peninsula continues to experience dangerous weather impacts, including strong wind gusts, torrential rain and persistent storm surge in some areas.
Areas of relentless heavy rain will continue to bring the threat of dangerous flash flooding in some areas. This threat becomes even more dangerous during overnight hours.
-ABC News' Dan Peck
There were at least 30 rescues in Naples, Florida, on Wednesday amid ongoing rescue operations, the Collier County Sheriff's Office said.
"Our East Naples deputies did 30 rescue missions today. We are still collecting numbers from other areas. We are still rescuing people," the office wrote on Facebook.
"Water is everywhere. It will recede. There will be damage," it added. "Tomorrow we will have a better idea of the extent of damage. We will keep you updated."
